This invention relates to a carding machine which includes a main carding cylinder having a clothed cylindrical jacket and at least two radial carrier elements. The carding machine further includes at least one clothed and/or non-clothed machine element facing the carding cylinder and two stationary lateral shield plates which support holding devices for the working element, for example, bends, stationary carding elements or cylinder covers.
The effective distance of the clothing points of the carding cylinder clothing from a machine element facing the clothing is defined as the carding gap or carding clearance. Such a machine element may also have a clothing but may be, for example, a shell segment having a smooth guiding surface. The size (width) of the carding gap is a significant machine parameter which affects both the fiber processing and the operating behavior of the machine. The carding gap is set to be as narrow as possible (it is measured in the tenths of millimeters) without, however, risking a collision between the working elements. To ensure a uniform processing of the fibers, the gap should be as uniform as possible over the entire working width of the carding machine.
The carding gap is affected particularly by the machine settings, on the one hand, and the condition of the clothing, on the other hand. The most important carding gap of a traveling flats-type carding machine is in the principal carding zone, that is, between the main carding cylinder and the traveling flats assembly.
In order to increase the output of the carding machine, it has been attempted to select the operational rpm or the operational velocity as high as permitted by the fiber processing technology. The working distance (carding gap) changes as a function of the operating conditions; the change occurs in the radial direction (as related to the rotary axis) of the carding cylinder.
In current carding processes the rate of processed fibers is continuously increased which requires increasingly higher velocities of the working organs and increasingly higher outputs of the individual, installed units of the carding machine. An increasing fiber output rate (production) leads, even if the working surfaces remain constant, to greater heat generation because of the increased mechanical work. At the same time, however, the technological carding result (sliver uniformity, degree of cleaning, reduction of neps, etc.) is continuously improved which requires a greater number of carding surfaces and narrower settings of the carding gaps of the working surfaces with respect to the main carding cylinder. Further, the proportion of chemical fibers to be processed steadily increases. During the carding process chemical fibers, because of greater friction, generate more heat than cotton as they contact the working faces of the carding machine. The working components of high-performance carding machines are in current designs fully encapsulated from all sides to comply with high safety requirements, to prevent particle emission into the blow room and to minimize machine maintenance. Grates or exposed material guiding surfaces which provided for an air exchange, belong to the past.
Due to the above-discussed circumstances, the heat input to the carding machine has significantly increased while the heat removal by convection has substantially dropped. The resulting stronger heat-up of high performance carding machines leads to greater thermoelastic deformations which, because of the non-uniform distribution of the temperature field, affect the set distances between the working surfaces. Thus, the distance between carding cylinder and traveling flats, doffer and stationary flats as well as separating locations decreases. In extreme cases heat expansion may even cause the set gap between the working surfaces to disappear entirely, and thus relatively moving machine components may collide, resulting in significant damages to the high performance carding machine. Furthermore, particularly the production of heat in the working region of the carding machine may lead to different thermal expansions if an excessive temperature difference between the structural components exists.
In a known device, as disclosed in European patent document 0 431 485, to which corresponds U.S. Pat. No. 5,127,134, a channel is provided through which a medium flows in order to remove heat from the flat bars or from a clothed or non-clothed shell component covering the cylinder. As a result of such an arrangement, in case of a heat expansion of the carding cylinder, the carding gap is disadvantageously even further reduced.
Further, a liquid transport system within the carding cylinder has been proposed to compensate for the temperature conditions at the external circumference of the carding cylinder. During operation an access to such a liquid transport system may occur only through the cylinder axis which substantially limits the possibilities to influence the conditions in the system, so that the object, that is, uniform temperature conditions, cannot be achieved. It is a further drawback that the system is very complex and expensive and the energy consumption for the cooling system is high.